Dariush Naghipour - School of Health, Guilan University of Medical Sciences Rasht, Iran
Kamran Taghavi - School of Health, Guilan University of Medical Sciences Rasht, Iran
Fatemeh Javan Mahjoub Doust - School of Health, Guilan University of Medical Sciences Rasht, Iran
Jalil Jaafari - School of Health, Guilan University of Medical Sciences Rasht, Iran

The present study focused on the usability of scallop shell coated Fe۲O۳ nanoparticles as an eco-friendly new absorbent in the treatment of tetracycline (TC). The process performance in terms of TC removal was investigated at different operating conditions i.e. at solution pH of ۷-۱۱, Fe۲O۳-scallop dosage of ۰.۴- ۲.۴ g L-۱, initial TC content of ۲۰-۱۲۰ mg L-۱, and temperature of ۲۵- ۵۵ ℃. Solution pH of ۷ yielded the highest TC removal efficiency (۹۹%). At this pH value, almost complete TC removal was achieved at a Fe۲O۳-scallop shell nanocomposite dose of ۱.۶ g L-۱, and ۲۵ C. The responsible TC removal mechanism suggested as the non-electrical - dispersion interaction between the bulk  system on the absorbent surface and TC molecules bearing both benzene rings and double bonds at this solution pH. TC removal efficiency appreciably enhanced up to the Fe۲O۳-scallop dosage of ۱.۶ g L-۱ being an optimum. Adsorption rate found to be fast at lower initial TC concentrations than ۴۰ mg L-۱. The effect of temperature on TC removal efficiency was insignificant. Adsorption followed the pseudo-second order kinetic model. Experimental data perfectly fitted by the Langmuir equation. The maximum adsorption capacity was calculated as ۴۹.۲۶ mg g-۱. Thermodynamic analysis demonstrated that adsorption process was a spontaneous process and endothermic. The results obtained from present study proved the excellent performance of scallop shell coated Fe۲O۳ nanoparticles as an eco-friendly adsorbent in TC treatment.